Chain saw



F. T. IRGENS March 12, 1968 CHAIN SAW 2 Sheets-Sheet 1 Filed Sept. 3, 1965 INVENTOR. fi/v/v T fe'qe/vs BY Arm, WV-

ArroPmH S March 12, 1968 F. 'r. IRGENS 3,372,718

CHAIN SAW Filed Sept. 5, 1965 2 Sheets-Sheet 3 BY Q -4 Q w W A TrOPn/EYS United States Patent 3,372,718 CHAIN SAW Finn T. Irgens, Milwaukee, Wis, assignor to Outboard Marine Corporation, Waukegan, 111., a corporation of Delaware Filed Sept. 3, 1965, Ser. No. 484,905

8 Claims. (Cl. 143-32) ABSTRACT OF THE DISCLOSURE Disclosed herein is a chain saw having a frame, a cutter bar carried on the frame and an internal combustion engine mounted on the frame, together with elastomeric means interposed between the frame and the engine for vibrationally isolating the engine from the frame and from the cutter bar. Rotatably mounted on the frame is a chain sprocket which is connected to the engine crank shaft by elastomeric means also adapted for vibrationally isolating the engine from the sprocket.

The invention relates to chain saws.

The invention provides a chain saw in which the engine housing and such components as are supported therefrom, such as the cutter bar and gripping handles, are vibrationally isolated from the engine mounted in the housing. Such an arrangement effectively isolates engine vibration from the operator. This advantage is particularly signiiicant under circumstances when the chain saw is in generally constant use by an operator, as for instance, in lumber jacking.

More particularly, one of the objects of the invention is to provide a chain saw including a frame or housing to which there is connected one or more handles, an internal combustion engine, and elastomeric means for supporting the engine from the housing in such manner as to isolate engine vibrations from the housing. In the preferred form of the invention, the chain sprocket is rotatably mounted on the frame or housing and a drive coupling including elastomeric means is employed for connecting the engine crankshaft and the chain sprocket in such manner as to afford power transmission while substantially avoiding engine vibration transmission. In addition, the frame or housing also contains a fuel tank and non-vibration transmitting means affording fuel supply to the engine from the tank.

Other objects and advantages of the invention will become known by reference to the following description and the accompanying drawings in which:

FIGURE 1 is a perspective view of a chain saw embodying various of the features of the invention;

FIGURE 2 is a fragmentary sectional view of the engine and other components incorporated in the chain saw shown in FIGURE 1;

FIGURE 3 is a view, partially in section, and taken at a right angle to FIGURE 2, of various of the components embodied in the chain saw shown in FIGURE 1;

FIGURE 4 is an enlarged fragmentary view, in section, taken along line 4-4 of FIGURE 1;

FIGURE 5 is an enlarged perspective view, partially broken away and in section, of the drive coupling conmeeting the engine crankshaft and a driveshaft supported by the chain saw housing; and

FIGURE 6 is an enlarged fragmentary view taken generally along line 6-6 of FIGURE 2.

Shown in the drawings is a chain saw 11 which embodies various of the features of the inventions and which includes a frame or engine housing 13 to which there is connected a pair of handles 15 and 17 which provide an operator with convenient means for gripping or holding of the chain saw. Preferably, as shown best in FIGURE 1, the handle 15 is generally of U shape and includes two free ends 19 adapted for engagement with the ground. The handle 17 extends generally perpendicularly to the plane of the handle 15 and includes a portion 21 which is also adapted to engage the ground, whereby there is provided a three-point support for the chain saw.

Supported within the housing 13 is an internal combustion engine 23 which is of the two-stroke type but may be of the four-stroke type and which includes an engine block 25 defining a cylinder 27 and a crankcase 29. Guided in the cylinder 27 is a piston 31 which is connected to a piston rod 33. In turn, the piston rod 33 is connected to a crankshaft 35 which extends through the crankcase 2.9, and is carried by suitable bearings 37 supported by the engine block 25. Also included in the engine is a flywheel 39 mounted on the crankshaft 35, a reed valve arrangement 41 for affording combustion-air-fuel-mixture flow to the crankcase 29, and a fan means or blower 43 carried on the crankshaft 35 for supplying combustion-air-fuelmixture for delivery through the reed valve arrangement 41 to the crankcase 29.

Supported by the frame or housing 13 are various components which are auxiliary to the engine 23 or which are driven by the engine. More specifically, in the specifically disclosed construction, the housing 13 is formed with a gear box portion 45 having bearings 47 supporting a driveshaft 49 carrying a pinion 51. Supported transversely of the driveshaft 49 within the gear box portion 45 on suitable bearings 53 is a cross shaft 55 which carries a gear 57 meshed with the pinion 51. At one end, the cross shaft 55 is connected to an engine starting device 59, such as a rewind starter, which device is mounted on the frame or housing 13. At its other end, the cross shaft 55 supports and is connected to a centrifugal clutch 61 which carries a saw chain drive sprocket 63. Also carried by the housing or frame 13 is a cutter bar 65 around the periphery of which there is trained a saw chain 67 which is driven by the chain sprocket 63.

Also included in the housing or frame 13 are an oil tank 68 (shown schematically in dotted outline) having a capped supply port 69 and a fuel tank '79 (shown schematically in dotted outline) having a capped supply port 71. The oii tank 68 can communicate with an oil pump (not shown) powered by the driveshaft: 49 and the fuel tank '76 communicates with a carburetor 73 (shown schematically in dotted outline in FIGURE 1).

In accordance with the invention, means are provided for supporting the engine 253 from the housing I3 so as to avoid transmission to the housing of engine vibration. While various arrangements can be employed, the disclosed construction employs a series of elastomeric mounts 75.

More specifically, as shown in FIGURES 3 and 4, the engine block 25 includes a series of hubs 77 and the frame or housing 13 includes a series of bosses 79 located in alignment with the hubs 77 on the engine block 25'.

In order also to avoid engine vibration transmission, an elastomeric connection is provided between the fan means or tblower 43 and the carburetor 73. In the particularly disclosed construction, as shown in FIGURE 6, the blower 43 includes a carbureted air inlet or supply port 91 to which there is connected a conduit 93 of resi liently flexible elastomeric material. Any suitable means, such as the wire clamp 94, can be employed to fix the conduit 93 and the part 91. In turn, the conduit 93 is connected to the carburetor 73 to provide a flow passage for the combustion-air-flow-mixture, while precluding transmission of engine vibration from the engine block 29 to the frame 13. If desired, the carburetor 73 can be mounted on the engine block 25 and connected to the fuel tank 70 by means of a flexible elastomeric conduit which will not transmit engine vibration from the engine block to the housing.

As the drive sprocket 63 in the disclosed construction is driven from the cross shaft 55 journalled in the gear box portion 45' of the housing or frame 13, means are provided for driving the cross shaft through a resilient connecting means or couplnig 95 which connects the crankshaft 35 and the driveshaft 49 without transmitting engine vibration therebetween. Various coupling arrangements can be employed. In the event the chain sprocket is supported directly from the engine block, such a coupling could be eliminated.

More specifically, with respect to the disclosed construction, the coupling 95 as shown best in FIGURES 2 and 5, includes an outer sleeve or annular member 97 which is of elastomeric material and which contains a centrally located disk 99 which is also of elastomeric material. Imbedded in or bonded to the disk are a plurality of prongs 101, of metal or other rigid material, which prongs extend axially from each of opposing faces of the disk 99. On each side of the disk 99, the prongs 101 are respectively received in annular rings 163 of elastomeric material. The rings 1% are respectively bonded to outer and inner metallic bushings 106 and 107. The outer bushings 105 are contained Within the outer sleeve member 97. The inner bushings 1tl7 include respective keys 109 which are respectively received in a key-way or slot 111 in the associated one of the crankshaft 35 and driveshaft 49.

During operation, the crankshaft 35 rotates the driveshaft 49 through the prongs 161 which are seated in the elastomeric annular rings 103. Because of the elastomeric connections, power transmission from the crankshaft 35 to the driveshaft 49 is accomplished while substantially avoiding transmission of engine vibration. Also during operation, the mounts 75 prevent the transmission of vibration from the engine to the housing. Thus, there is provided a chain saw in which the vibratory action of the engine resulting from operation thereof is isolated from the outer portions of the chain saw which are held by the operator. In addition, the engine vibrations are also isolated from the saw chain so as to provide a uniform cutting action.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

1. In a chain saw, the combination of a frame, a cutter bar mounted on said frame, a chain sprocket rotatably mounted on said frame, a saw chain extending around said sprocket and said cutter bar an internal combustion engine mounted on said frame and having a crankshaft, means rotatably drivingly connecting said crankshaft and said chain sprocket, and elastomeric means interposed between said frame and said engine and between said crankshaft and said chain sprocket for vibrationally isolating said engine from said frame and from said cutter bar.

2. In a chain saw, the combination of a frame, a cutter bar on said frame, a chain sprocket rotatably mounted on said frame, an internal combustion engine having la crankshaft, elastomeric means supporting said engine from said frame, and elastomeric means rotatably drivingly connecting said crankshaft and said chain sprocket, whereby said frame, said cutter bar, and said sprocket are vibrationally isolated from said engine.

3. In a chain saw, the combination of a frame, a cutter bar on said frame, a chain sprocket rotatably mounted on said frame, an internal combustion engine having a crankshaft, elastomeric means connecting said frame and said engine for supporting and vibrationally isolating said engine from said frame, and resilient means rotatably drivingly connecting said crankshaft and said chain sprocket and vibrationally isolating said chain sprocket from said crankshaft.

4. In a saw chain, the combination of a frame, a chain sprocket rotatably mounted on said frame, a cutter bar on said frame, a saw chain trained around said sprocket and guided by said cutter bar, a fuel tank on said frame, an internal combustion engine having a crankshaft and a fuel inlet, means connecting said frame and said engine for supporting and vibrationally isolating said engine from said frame and from said cutter bar, conduit means for connecting said fuel tank and said inlet to afford fuel flow to said engine and for vibrationally isolating said fuel tank from said engine, and elastomeric means drivingly connecting said crankshaft and said sprocket.

5. In a chain saw, the combination of a frame, a cutter bar on said frame, a chain sprocket rotatably mounted on said frame, a carburetor on said frame, an internal combustion engine having a crankshaft and a carbureted air inlet, elastomeric means connecting said frame and said engine for supporting and vibrationally isolating said engine from said frame, resilient means drivingly connecting said crankshaft and said sprocket and vibrationally isolating said sprocket from said crankshaft, and flexible conduit means connecting said carburetor and said carbureted air inlet to afford flow of carbureted air from said carburetor to said engine and to vibrationally isolate said carburetor from said engine.

6. In a chain saw, the combination of a frame, a cutter bar on said frame, a chain sprocket rotatably mounted on said frame, an engine starting device mounted on said frame, a driveshaft rotatably mounted on said frame and drivingly connected to said sprocket and said starting device, an internal combustion engine having a crankshaft, elastomeric means connecting said frame and said engine for supporting and vibrationally isolating said engine from said frame and from said cutter bar, and resilient means drivingly connecting said crankshaft and said driveshaft and vibrationally isolating said driveshaft from said crankshaft.

7. In a chain saw, the combination of a frame, a cutter bar on said frame, a chain sprocket rotatably mounted on said frame, an engine starting device mounted on said frame, a driveshaft rotatably mounted on said frame and drivingly connected to said sprocket and said starting device, a carburetor mounted on said frame, an internal combustion engine having a crankshaft and a carbureted air inlet, elastomeric means connecting said frame and said engine for supporting and vibrationally isolating said engine from said frame, resilient means drivingly connecting said crankshaft and said driveshaft and vibrationally isolating said driveshaft from said crankshaft, and flexible conduit means connecting said carburetor and said carbureted air inlet to afford flow of carbureted air from said carburetor to said engine and to vibrationally isolate said carburetor from said engine.

8. In a chain saw, the combination of a frame, a cutter bar on said frame, an oil tank on said frame, a gas tank on said frame, a handle on said frame, a chain sprocket rotatably mounted on said frame, an engine starting device on said frame, a driveshaft rotatably mounted on said frame and drivingly connected to said sprocket and said starting device, a carburetor on said frame, an internal combustion engine having a crankshaft, and a carbureted air inlet, elastomeric means connecting said References Cited frame and said engine for supporting and vibration-ally UNITED STATES PATENTS isolating said engine from said frame, resilient means drivingly connecting said crankshaft and said drivesha'ft 2 1/1924 Smlth t? and vibrationally isolating said dri-veshaft from said 5 5/1932 6 7 crankshaft, and flexible conduit means connecting said 7/1964 LiFome 173-162 3,157,211 11/1964 Wng 143---32 carburetor and said carbureted air inlet to afford flow of 3 224 3 2 1 65 3 3 carbureted air from said carburetor to said engine and 1 9 Dobbemn et 14 2 to vibration-ally isolate said carburetor from said engine. DONALD R. SCHRAN, Primary Examiner. 

